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GoQBot soft-bodied robot inspired by caterpillars

By Damir Beciri

27 April 2011

Despite their extreme flexibility and adaptability, current soft-bodied robots are often limited by their slow speed. Inspired by the ability of some caterpillars to rapidly curl themselves into a wheel and propel themselves away from predators, a team of researchers from the Tufts University, Massachusetts, have developed GoQBot – a soft-bodied robot with a similar ability.

This highly dynamic process, called ballistic rolling, is one of the fastest wheeling behaviors in nature. To simulate the movement of a caterpillar, the researchers designed a 10-cm (4-inch) long soft-bodied robot made out of silicone rubber and actuated by embedded shape memory alloy coils. The robot got its name because it forms a “Q” shape before rolling away at speed of over half a meter per second (1.64 feet per second).

The GoQBot was designed to specifically replicate the functional morphologies of a caterpillar, and was fitted with 5 infrared emitters along it side to allow motion tracking using one of the latest high speed 3D tracking systems. Simultaneously, a force plate measured the detailed ground forces as the robot pushed off into a ballistic roll.

The robot is able to change its body conformation in less than 100ms, thus it benefits from a significant degree of mechanical coordination in ballistic rolling. Researchers believe such coordination is mediated by the nonlinear muscle coupling in the animals.

The researchers were also able to explain why caterpillars don’t use the ballistic roll more often as a default mode of transport. They have figured that despite its impressive performance, ballistic rolling is only effective on smooth surfaces, demands a large amount of power, and often ends unpredictably.

Many modern robots are modeled after snakes, worms and caterpillars for their ability to climb or crawl into hardly accessible spaces. However, the limbless bodies severely reduce the speeds of the robots in the opening. On the other hand, there are many robots that employ a rolling motion in order to travel with speed and efficiency, but they struggle to gain access to difficult spaces.

“GoQBot demonstrates a solution by reconfiguring its body and could therefore enhance several robotic applications such as urban rescue, building inspection, and environmental monitoring”, said Huai-Ti Lin from the Department of Biology, Tufts University. “Due to the increased speed and range, limbless crawling robots with ballistic rolling capability could be deployed more generally at a disaster site such as a tsunami aftermath. The robot can wheel to a debris field and wiggle into the danger for us.”